Cholangitis

Acute cholangitis develops when bile flow is obstructed and bacteria ascend from the duodenum into the stagnant biliary tree. The most common cause is a gallstone lodged in the common bile duct (choledocholithiasis); strictures, tumors, and manipulation during endoscopic procedures are other causes. The usual organisms are enteric gram-negative rods — Escherichia coli and Klebsiella species — along with Enterococcus and anaerobes such as Bacteroides.

The classic presentation is Charcot triad: right upper quadrant pain, fever, and jaundice. When infection progresses to biliary sepsis, hypotension and altered mental status are added to form Reynolds pentad, which signals severe disease. Laboratory findings show a cholestatic pattern — elevated alkaline phosphatase, gamma-glutamyl transferase, and direct (conjugated) bilirubin — with leukocytosis and often positive blood cultures. Ultrasound is the usual first imaging test, looking for duct dilation and stones.

Management combines intravenous antibiotics and fluid resuscitation with biliary decompression, typically by ERCP with stone extraction or stent placement; delayed drainage in severe cases carries high mortality. A separate chronic entity, primary sclerosing cholangitis, causes progressive fibrosis and stricturing of intra- and extrahepatic ducts. It is strongly associated with ulcerative colitis, shows a characteristic "beaded" appearance on cholangiography, may be associated with p-ANCA, and substantially raises the risk of cholangiocarcinoma.

USMLE Step 1 vignettes commonly present a patient with fever, jaundice, and right upper quadrant pain and ask you to distinguish cholangitis from acute cholecystitis — cholecystitis typically lacks jaundice and features a positive Murphy sign — or to link primary sclerosing cholangitis to ulcerative colitis and downstream cholangiocarcinoma risk.